Conventionally, this type of document feeder mounted on a platen glass of a copying apparatus has a transport section where a document is pressed on the surface of the platen glass by a white endless belt and is conveyed by the rotation of the belt. More specifically, in the transport section, the endless belt covers the whole surface of the platen glass to press a document on the glass, and is slightly loosened to produce the frictional force at the proper positions of the surface of the document, whereby the document is allowed to be fed. Accordingly, the conventional document feeder has the following problems;
(1) Since the thickness is required to be enough for rotation of the belt, the total height of the feeder becomes high, resulting in a large-sized apparatus.
(2) The pressing force of the belt is reduced gradually due to fatigue and deterioration and frequently causes problems due to a decrease in its elasticity, resulting in unsatisfactory serviceability.
(3) The belt rotates while sliding on the platen glass. This requires a large high-powered motor.
Therefore, the inventors of the present invention previously proposed a document feeder, which was mounted on a copying apparatus and had a white sheet over a platen glass. In that feeder, document transport rollers were in contact with the surface of the platen glass through holes formed at the proper positions on the sheet.
With that document feeder, in the transport portion, a document entered a gap between the white sheet and the surface of the platen glass to be pressed and conveyed. However, in the transport portion the surface of the sheet and a document come into contact with each other, thereby producing frictional force and static electricity. Accordingly, there was the possibility of causing such problems as preventing the document from being conveyed or becoming askew.
In consideration of the above problems, the object of the invention is to provide a document feeder having no possibility of causing problems due to friction and static electricity between the white sheet and a document.